Provocations Escalate on Korean Peninsula

SEOUL—The two Koreas escalated mutual threats on Friday, in an early test of South Korean President Park Geun-hye's pledge to open a new era of trust with the North.

A day after the U.N. Security Council imposed stricter sanctions on North Korea in response to its Feb. 12 nuclear test, Pyongyang said it would sever its main hotline with South Korea and scrap agreements on peaceful resolution of conflict, including a 1991 pact that...